1. Field of the Invention
The present invention relates to a planar image display device which makes use of the emission of electrons into a vacuum formed between a face substrate and a back substrate, and more particularly to an image display device which arranges a plurality of distance holding members in the vacuum formed between both substrates.
2. Description of the Related Art
A color cathode ray tube has been popularly used conventionally as an excellent display device which exhibits high brightness and high definition. However, along with the realization of high image quality of recent information processing device and television broadcasting, there has been a strong demand for a planar image display device (flat·panel·display, FPD) which is light-weighted and requires a small space for installation while ensuring the excellent properties such as high brightness and high definition.
As typical examples of such a planar image display device, a liquid crystal display device, a plasma display device or the like has been put into practice. Further, particularly with respect to the planar display device which can realize the high brightness, with respect to a self luminous display device which makes use of emission of electrons into vacuum from electron sources, various planar image display devices such as an electron emission type image display device, a field emission type image display device, an organic EL display which are characterized by low power consumption and the like are expected to be put into practice in near future.
Among these planar image display devices, with respect to the self-luminous flat panel display, there has been known a display device having the constitution in which electron sources are arranged in a matrix array, wherein as one such display, there has been also known the above-mentioned electron emission image display device which makes use of minute and integrative cold cathodes.
Further, in the self-luminous flat panel display, as cold cathodes, thin film electron sources of a spindle type, a surface conduction type, a carbon nanotubes type, an MIM (Metal-Insulator-Metal) type which laminates a metal layer, an insulator and a metal layer, an MIS (Metal-Insulator-Semiconductor) type which laminates a metal layer, an insulator and a semiconductor layer, a metal-insulator-semiconductor layer-metal or the like has been used.
With respect to the MIM type electron source, for example, there has been known an electron source which is disclosed in Japanese Patent Laid-open Hei7(1995)-65710 (patent document 1) and Japanese Patent Laid-open Hei10(1998)-153979 (patent document 2), for example. Further, with respect to the metal-insulator-semiconductor electron source, there has been known an MOS type electron source reported in j. Vac. Sci. Technol. B11 (2) p. 429-432 (1993) (non-patent document 1). Further, with respect to the metal-insulator-semiconductor-metal type electron source, there has been known a HEED type electron source reported in high-efficiency-electro-emission device, Jpn. J. Appl. Phys., vol 36, pL939 (non-patent document 2), an EL type electron source reported in Electroluminescence, Applied Physics, Volume 63, No. 6, p. 592 (non-patent document 3), or a porous silicon type electron source reported in Applied Physics, Volume 66, No. 5, p. 437 (non-patent document 4).
As the electron emission type FPD, there has been known a display panel which is constituted of a back substrate which includes the electron sources described above, a face substrate which includes phosphor layers and an anode to which an acceleration voltage for allowing electrons emitted from electron sources to impinge on the phosphor layers is applied, and a support body which allows the back substrate and the face substrate to face each other in an opposed manner and constitutes a sealing frame for sealing an inner space formed by opposing surfaces of both substrates into a given vacuum state. The electron emission type FPD is operated in a state that drive circuits are combined with the display panel.
In the image display device having the MIM type electron sources, the above-mentioned back substrates includes a substrate formed of an insulation material, wherein on the substrate, a plurality of scanning signal lines which extend in one direction, are arranged in parallel in another direction which is orthogonal to one direction, and to which scanning signals are applied sequentially in another direction are formed. Further, on the substrate, a plurality of image signal lines which extend in the above-mentioned another direction and are arranged in parallel in the above-mentioned one direction to intersect the scanning signal lines are formed. The above-mentioned electron sources are formed in the vicinity of respective intersecting portions of the scanning signal lines and the image signal lines, and both lines and the electron sources are connected through energizing electrodes and hence, an electric current is supplied to the electron sources.
The individual electron source forms a pair with a corresponding phosphor layer so as to constitute a unit pixel. Usually, one pixel (color pixel) is constituted of the unit pixels of three colors consisting of red (R), green (G) and blue (B). Here, in the case of the color pixel, the unit pixel is also referred to as a sub pixel.
In the planner image display device described above, in general, in the inside of a display region which is arranged between the back substrate and the face substrate and is surrounded by the support body, a plurality of distance holding members (hereinafter referred to as spacers) are arranged and fixed thus holding the distance between the above-mentioned both substrates at a given distance in cooperation with the support body. The spacers are formed of a plate-like body which is made of an insulation material such as glass, ceramics or the like, in general. Usually, the spacers are arranged at positions which do not impede an operation of pixels for every plurality of pixels.
Further, with respect to the planner image display device, there has been proposed a display panel which connects spacers having semiconductor characteristics by connecting the spacers with electrodes in Japanese Patent 3305166 Publication (patent document 3).
Further, with respect to the planner image display device, the constitution which forms a conductive film which melts a conductive material over a bottom surface from side surfaces of a wall body has been proposed in U.S. Pat. No. 6,225,737 Specification (patent document 4).